1. Technical Field
The present invention relates to a method for manufacturing a semiconductor chip and a method for manufacturing an electronic module comprising a substrate, at least one conductive element integral with the substrate and a semiconductor chip.
The present invention particularly relates to the manufacturing of a thin electronic module and more particularly a “contactless”-type module enabling various types of contactless portable objects to be produced, such as contactless smart cards, contactless electronic badges, contactless electronic tags, etc. Such a module can also be inserted into identification objects such as passports or identity cards.
2. Description of the Related Art
An integrated circuit comes in the form of a silicon chip that comprises an active face onto which an integrated circuit region is implanted, forming the actual integrated circuit, and contact pads electrically linked to the integrated circuit region.
An electronic module is produced by electrically linking the contact pads of the chip to one or more conductors integral with an interconnection support, which are themselves linked to other electronic components. However, in the case of a contactless electronic module, the conductor or conductors of the interconnection support are not generally linked to other electronic components (except for passive electric components of capacitor or self-inductance type) but form an antenna circuit interfacing between the integrated circuit and the external environment, for receiving and/or sending data.
The chip is generally mounted bare onto the interconnection support, without previously being arranged in a protection case, and the electric connection of the contact pads with the interconnection support is generally obtained by means of the “chip and wire” technique or the “flip chip” technique. In the first case, the chip is fixed onto the interconnection support with its active face facing upwards, and its contact pads are linked to the conductors of the interconnection support using ultrasonic wire bonding. In the second case, the chip is reverse mounted onto the interconnection support and its contact pads are directly bonded onto corresponding conductive pads of the interconnection support, for example by pressing, applying ultrasonic vibrations, fusion of a material like lead tin or even sticking (by means of an electrically conductive glue).
The mounting of a chip by ultrasonic wiring has the disadvantage that the loops formed by the wires generally have a height greater than the thickness of the chip and increase the total thickness of the micro-module. Furthermore, the wires must be coated in a protection resin that increases the total thickness of the assembly. The “flip-chip” mounting of a chip is therefore often preferred to ultrasonic wiring. However, despite its advantages, the flip-chip technique does not enable electronic modules to be produced with a thickness sufficiently slight to be suitable to all applications, particularly contactless-type modules that are to be integrated into very thin supports (sheet of paper, card or plastic, etc.), despite recent progress in the thinning of chips and the use of new materials (paper, polymers) to form very thin substrates. Another parameter affecting the final thickness of a “flip chip” module is the thickness of the conductive material bumps (or “balls”, etc.) which are interposed between the contact pads of the chip and the surface of the interconnection support.